DESCRIPTION: The long-term goal of the proposed research is to determine the genetic and molecular bases of cholinergic neuronal function in the soil nematode Caenorhabditis elegans. The focus of the present research is on the cholinergic locus, which contains 2 genes: cha-1 is the structural gene for choline acetyltransferase (ChAT), the enzyme which synthesizes the neurotransmitter acetylcholine, and unc-17 is the gene which encodes the synaptic vesicle acetylcholine transporter. The research has 6 primary aims: 1) To study the development of the cholinergic nervous system during embryonic and postembryonic development by monitoring the appearance of cholinergic markers. 2, 3) To identify trans-acting factors involved in the control and expression of the cholinergic phenotype. 4, 5) To study the contribution of specific classes of cholinergic neurons to the overall function of the nervous system and behavior of the organism. 6) To investigate the role of a neuron's transmitter on the development of the neuron. The proposed research will provide a molecular and genetic analysis of how neurons become cholinergic neurons and should elucidate the processes by which neurons become differentiated and achieve a common neurotransmitter identity.